This invention relates to a cooling tower of a novel structure, whether in the form of a hyperbolic paraboloid or of some other shape, to a method for erecting such towers, and to a novel precast unit which plays an important part in the structure and which can be integrated by reinforcing or by prestressing or both.
High towers of hyperbolic paraboloid shape, as well as of other shapes, have been constructed for the purpose of cooling water which has been heated in a nuclear or in a fossil-fuel type of power plant. When the hot water is sprayed from nozzles inside the tower at a relatively low level, a flow of air is induced by the heat of the water, the air entering at the lower end of the tower through an open work portion and rising through the tower, thereby cooling the water so that it can be reused in the power plant or be put into streams as cool water.
These cooling towers are quite large, being several hundred feet high, and have heretofore been made either by poured-in-place concrete or by a combination thereof with precast units, and such towers have necessarily consumed a large amount of steel for reinforcement and strength. In spite of all this, in spite of the fact that smooth concrete walls of various thicknesses which have heretofore been used in such cooling towers have been ten inches or even more in thickness, and in spite of the enormous amount of both concrete and steel used, still those towers that have been erected have not been provided with sufficient resistance to earthquakes or even wind.
Those towers have been very expensive, both in the consumption of material and in the cost of erection, due to such factors as the enormous amount of steel to be erected, the enormous amount of concrete to be poured, the time intervals required for the concrete in lower portions to set sufficiently to be able to support later poured concrete portions thereabove, the very large amount of concrete that has had to be lifted by cranes to be poured, and the substantial labor costs resulting from the insufficient, time-consuming construction methods that have been used heretofore.